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package java.beans;

/**
 * A PropertyEditor class provides support for GUIs that want to
 * allow users to edit a property value of a given type.
 * <p>
 * PropertyEditor supports a variety of different kinds of ways of
 * displaying and updating property values.  Most PropertyEditors will
 * only need to support a subset of the different options available in
 * this API.
 * <P>
 * Simple PropertyEditors may only support the getAsText and setAsText
 * methods and need not support (say) paintValue or getCustomEditor.  More
 * complex types may be unable to support getAsText and setAsText but will
 * instead support paintValue and getCustomEditor.
 * <p>
 * Every propertyEditor must support one or more of the three simple
 * display styles.  Thus it can either (1) support isPaintable or (2)
 * both return a non-null String[] from getTags() and return a non-null
 * value from getAsText or (3) simply return a non-null String from
 * getAsText().
 * <p>
 * Every property editor must support a call on setValue when the argument
 * object is of the type for which this is the corresponding propertyEditor.
 * In addition, each property editor must either support a custom editor,
 * or support setAsText.
 * <p>
 * Each PropertyEditor should have a null constructor.
 */

public interface PropertyEditor {

  /**
   * Set (or change) the object that is to be edited.  Primitive types such
   * as "int" must be wrapped as the corresponding object type such as
   * "java.lang.Integer".
   *
   * @param value The new target object to be edited.  Note that this object should not be modified
   * by the PropertyEditor, rather the PropertyEditor should create a new object to hold any
   * modified value.
   */
  void setValue(Object value);

  /**
   * Gets the property value.
   *
   * @return The value of the property.  Primitive types such as "int" will be wrapped as the
   * corresponding object type such as "java.lang.Integer".
   */

  Object getValue();

  //----------------------------------------------------------------------

  /**
   * Determines whether this property editor is paintable.
   *
   * @return True if the class will honor the paintValue method.
   */

  boolean isPaintable();

  /**
   * Paint a representation of the value into a given area of screen
   * real estate.  Note that the propertyEditor is responsible for doing
   * its own clipping so that it fits into the given rectangle.
   * <p>
   * If the PropertyEditor doesn't honor paint requests (see isPaintable)
   * this method should be a silent noop.
   * <p>
   * The given Graphics object will have the default font, color, etc of
   * the parent container.  The PropertyEditor may change graphics attributes
   * such as font and color and doesn't need to restore the old values.
   *
   * @param gfx Graphics object to paint into.
   * @param box Rectangle within graphics object into which we should paint.
   */
  void paintValue(java.awt.Graphics gfx, java.awt.Rectangle box);

  //----------------------------------------------------------------------

  /**
   * Returns a fragment of Java code that can be used to set a property
   * to match the editors current state. This method is intended
   * for use when generating Java code to reflect changes made through the
   * property editor.
   * <p>
   * The code fragment should be context free and must be a legal Java
   * expression as specified by the JLS.
   * <p>
   * Specifically, if the expression represents a computation then all
   * classes and static members should be fully qualified. This rule
   * applies to constructors, static methods and non primitive arguments.
   * <p>
   * Caution should be used when evaluating the expression as it may throw
   * exceptions. In particular, code generators must ensure that generated
   * code will compile in the presence of an expression that can throw
   * checked exceptions.
   * <p>
   * Example results are:
   * <ul>
   * <li>Primitive expresssion: <code>2</code>
   * <li>Class constructor: <code>new java.awt.Color(127,127,34)</code>
   * <li>Static field: <code>java.awt.Color.orange</code>
   * <li>Static method: <code>javax.swing.Box.createRigidArea(new
   * java.awt.Dimension(0, 5))</code>
   * </ul>
   *
   * @return a fragment of Java code representing an initializer for the current value. It should
   * not contain a semi-colon ('<code>;</code>') to end the expression.
   */
  String getJavaInitializationString();

  //----------------------------------------------------------------------

  /**
   * Gets the property value as text.
   *
   * @return The property value as a human editable string. <p>   Returns null if the value can't be
   * expressed as an editable string. <p>   If a non-null value is returned, then the PropertyEditor
   * should be prepared to parse that string back in setAsText().
   */
  String getAsText();

  /**
   * Set the property value by parsing a given String.  May raise
   * java.lang.IllegalArgumentException if either the String is
   * badly formatted or if this kind of property can't be expressed
   * as text.
   *
   * @param text The string to be parsed.
   */
  void setAsText(String text) throws java.lang.IllegalArgumentException;

  //----------------------------------------------------------------------

  /**
   * If the property value must be one of a set of known tagged values,
   * then this method should return an array of the tags.  This can
   * be used to represent (for example) enum values.  If a PropertyEditor
   * supports tags, then it should support the use of setAsText with
   * a tag value as a way of setting the value and the use of getAsText
   * to identify the current value.
   *
   * @return The tag values for this property.  May be null if this property cannot be represented
   * as a tagged value.
   */
  String[] getTags();

  //----------------------------------------------------------------------

  /**
   * A PropertyEditor may choose to make available a full custom Component
   * that edits its property value.  It is the responsibility of the
   * PropertyEditor to hook itself up to its editor Component itself and
   * to report property value changes by firing a PropertyChange event.
   * <P>
   * The higher-level code that calls getCustomEditor may either embed
   * the Component in some larger property sheet, or it may put it in
   * its own individual dialog, or ...
   *
   * @return A java.awt.Component that will allow a human to directly edit the current property
   * value.  May be null if this is not supported.
   */

  java.awt.Component getCustomEditor();

  /**
   * Determines whether this property editor supports a custom editor.
   *
   * @return True if the propertyEditor can provide a custom editor.
   */
  boolean supportsCustomEditor();

  //----------------------------------------------------------------------

  /**
   * Adds a listener for the value change.
   * When the property editor changes its value
   * it should fire a {@link PropertyChangeEvent}
   * on all registered {@link PropertyChangeListener}s,
   * specifying the {@code null} value for the property name
   * and itself as the source.
   *
   * @param listener the {@link PropertyChangeListener} to add
   */
  void addPropertyChangeListener(PropertyChangeListener listener);

  /**
   * Removes a listener for the value change.
   *
   * @param listener the {@link PropertyChangeListener} to remove
   */
  void removePropertyChangeListener(PropertyChangeListener listener);

}
